Solar Panel immersion heater automatic switch.

[thushar]

madmug - do you have a schematic of the circuit ? I found it practically difficult to do a proportional circuit

 

[madmurg]

madmug - do you have a schematic of the circuit ? I found it practically difficult to do a proportional circuit

this is a link to the schematic of the current circuit

Detailed energy monitor system design | OpenEnergyMonitor
you make this circuit board and the take a cable from the pwm arduino pin to the 0-5v of the proportional controller.

 

[thushar]

Thank you for that

Where can i find the proportional controller ? Also, the total construction cost of this kit will goes above £100 ?

 

[madmurg]

Thank you for that

Where can i find the proportional controller ? Also, the total construction cost of this kit will goes above £100 ?

the electronics cost only £2
2 cts £14
I found a controller on ebay for £11 but for a new one you are looking at about £70

 

[thushar]

the electronics cost only £2
2 cts £14
I found a controller on ebay for £11 but for a new one you are looking at about £70

"the electronics cost only £2" - Did you forgot to include the cost of the Arduino microcontroller

Looks like proportional controller is hard to find , the one that i just found online was about £300!!

 

[methley]

Available from Farnell...

http://uk.farnell.com/crydom/10pcv2425/ssr-240vac-25a-2-10vdc/dp/1936419

 

[thushar]

Cool .. Thank you.

Could we do the entire system with the 2 CT's + controller and without using a microcontroller ? any comparator circuits using LM series ?

 

[madmurg]

Cool .. Thank you.

Could we do the entire system with the 2 CT's + controller and without using a microcontroller ? any comparator circuits using LM series ?

not that I know of I think the only way to calculate real power and control the proportional controller is to use software.

 

[thushar]

ok. Are you using this setup to heat the water? Does the controller heats up during working ? Also, How do you fine tune it ?

Thanks for the great help

 

[TechyTim]

Hi,
This is a fine solution if you don't mind building it yourself as a commercial version is not yet available for several reasons:
1. Phase angle controls can generate EMC problems which would have to be filtered out at some cost;
2. A commercial controller would need to be tested for CE marking at some cost;
3. Getting a reliable source of mains power used is very difficult with modern installations, just measuring current will give false import and export readings as there is no sign from a standard CT, e.g. 8A generated and 5A on grid, could be export of 5A or import of 5A to meet 13A load.

TT.

 

[danesol]

Just found Solar Panel Immersion Heater Switch - Use Surplus Power To Heat Water | eBay
Has anyone tried one of these?
Do not know if there is any garantee with it but have asked the question.
To be cost effective it has got to last several years

Also I assume "NO use" if your PV is in a different building or area to where you have your immersion heater / CU, unless the clip on sensor is Bluetooth or RF controlled ??

 

[Del Boy]

I wouldn't buy the £168 + £8 p&p ebay one as there's a good chance it will be running your immersion heater off the grid. If you pay 3p/kW for gas and 15p/kW for electric then running this off the mains at a 1:5 ratio or for 10 mins per hour will negate any savings made. Anything more than 10 mins for hour of greater than 500W baseload at your property (kettles, TVs etc on-top of fridges/freezers) will start actually costing you money!

I'm amazed it's sold so many, especially as you could do the same by simply flicking the switch on your immersion heater when your solar meter is saying 1.5kW or greater. You'd probably be better off with a timer from Argos which you only turn on during peak hours and turn it off when the weather forecast is bad.

Anyways... I've been looking into this and you will need a 1kW immersion heater ideally rather than the 3kW most people have. I've looked into stepping a 3kW down to 1kW via 220 to 110V, but it's not cost-efficient.

I'm looking to make one of these for myself, which will automatically turn on the immersion heater when the solar is exporting 1kW or more. It will automatically turn off at below 1kW export, so will never take electricity from the grid. If anyone, would like me to try and make one for them, please PM me. I'll probably need some pics of your install (consumer unit, gen meter etc) and details of what exactly you want. My install is going to be quite simple but I don't mind making it a bit more complicated for your needs if I can.

Bear in mind... I will be doing this as a hobby not a business!!! So please be kind!!!

 

[madmurg]

I wouldn't buy the £168 + £8 p&p ebay one as there's a good chance it will be running your immersion heater off the grid. If you pay 3p/kW for gas and 15p/kW for electric then running this off the mains at a 1:5 ratio or for 10 mins per hour will negate any savings made. Anything more than 10 mins for hour of greater than 500W baseload at your property (kettles, TVs etc on-top of fridges/freezers) will start actually costing you money!

I'm amazed it's sold so many, especially as you could do the same by simply flicking the switch on your immersion heater when your solar meter is saying 1.5kW or greater. You'd probably be better off with a timer from Argos which you only turn on during peak hours and turn it off when the weather forecast is bad.

Anyways... I've been looking into this and you will need a 1kW immersion heater ideally rather than the 3kW most people have. I've looked into stepping a 3kW down to 1kW via 220 to 110V, but it's not cost-efficient.

I'm looking to make one of these for myself, which will automatically turn on the immersion heater when the solar is exporting 1kW or more. It will automatically turn off at below 1kW export, so will never take electricity from the grid. If anyone, would like me to try and make one for them, please PM me. I'll probably need some pics of your install (consumer unit, gen meter etc) and details of what exactly you want. My install is going to be quite simple but I don't mind making it a bit more complicated for your needs if I can.

Bear in mind... I will be doing this as a hobby not a business!!! So please be kind!!!

you do not need a 1kw immersion heater you can still use your 3kw immersion with the correct solar controller.
my unit uses spare power right down to 400w so on a cloudy day it will still give you a tank of warm water. On a sunny day I get a tank of hot water. It is usable all through the winter.
using a 3kw immersion will still give you a tank of hot water with say 1.5kw spare power, it will just take longer to heat up.

 

[yellowvanman]

Anyways... I've been looking into this and you will need a 1kW immersion heater ideally rather than the 3kW most people have. I've looked into stepping a 3kW down to 1kW via 220 to 110V, but it's not cost-efficient.

A site transformer only costs about £60-£70

 

[Del Boy]

Thanks for the replies guys. A site transformer would make it a lot easier but I'm going to have to do some calcs to see whether 700W immersion is going to be sufficient for different size PVs. A solar controller would be ideal but I'm not sure the cost will payback... more sums for me to do.

I'll spend some time on PVOutput and see what difference in benefit there is for each solution.

I'm hoping to have my own one up and running within a few weeks... will keep you all updated!